QA/QC in Bridge Design - Getting it Right. Thomas C. Stout TxDOT Bridge Division Design 2012 Short Course

Transcription

1 QA/QC in Bridge Design - Getting it Right Thomas C. Stout TxDOT Bridge Division Design 2012 Short Course

2 Outline 1. The need for QA/QC 2. Definitions 3. QC as it applies to bridge design 4. QA for the Bridge Division Design Section 5. Records retention

3 Outline 1. The need for QA/QC 2. Definitions 3. QC as it applies to bridge design 4. QA for the Bridge Division Design Section 5. Records retention

4 So, why do we care about Quality Assurance & Quality Control?

5 So, why do we care about Quality Assurance & Quality Control?

6 I-35W Bridge Over the Mississippi River August 1 st, 2007

7 NTSB Highway Accident Report Probable Collapse Causes Insufficient bridge design firm quality control Lack of guidance on placement of construction loads Exclusion of gusset plates in load rating Lack of inspection guidance Inadequate use inspection technology

8 NTSB Highway Accident Report Probable Collapse Causes Insufficient bridge design firm quality control Lack of guidance on placement of construction loads Exclusion of gusset plates in load rating Lack of inspection guidance Inadequate use inspection technology

9 NTSB Highway Accident Report Report Recommendations Implement a design QA/QC program Require load ratings of new bridges Evaluate gusset plates in load rating Control construction activities to avoid overloading structures

10 NTSB Highway Accident Report Report Recommendations Implement a QA/QC program Require load ratings of new bridges Evaluate gusset plates in load rating Control construction activities to avoid overloading structures

11 New London, Texas School Explosion March 18, 1937 Natural gas explosion 300 deaths Resulted in the Engineering Registration Act, now rewritten as the Texas Engineering Practices Act

12 Route 35 Silver Bridge Collapse December 15, 1967 Stress corrosion cracking in a non-redundant member 46 deaths In 1968 Congress passed the Federal Highway Act: US Code Title 23 Section 151 that set forth the requirement to establish National Bridge Inspection Standards (NBIS)

13 Outline 1. The need for QA/QC 2. Definitions 3. QC as it applies to bridge design 4. QA for the Bridge Division Design Section 5. Records retention

14 quality (qual i ty) /ˈkwälətē/ the standard of something as measured against other things of a similar kind; the degree of excellence of something; general excellence of standard or level

15 assurance (as sur ance) /əˈsho orəns/ a positive declaration intended to give confidence; a promise; confidence or certainty in one s own abilities

16 control (con trol) /kənˈtrōl/ the power to influence or direct people s behavior or the course of events; the restriction of an activity, tendency, or phenomenon

17 What s the difference? Quality Assurance The planned and systematic activities implemented in a quality system so that quality requirements for a product or service will be fulfilled Quality Control The observation techniques and activities used to fulfill requirements for quality

18 What s the difference? Quality Assurance QA is a failure prevention system QA defines the standards/methodology QA activities are done before the product is manufactured Quality Control QC is a failure detection system QC ensures that the standards are followed QC activities are done during the manufacturing process

19 What s the difference? Quality Assurance QA is process oriented QA makes sure you are doing the right things, the right way QA tasks are conducted by managers Quality Control QC is product oriented QC makes sure the results of what you've done are what you expected QC tasks are executed by experts who are directly involved with the design

20 Behold the BRG QA/QC Guide! bus/bridge/qa_qc _guide.pdf

21 Stated Goals Communicate openly to solve problems immediately Plan, coordinate, supervise, and provide technical direction Employ skilled personnel to produce a quality product Produce quality work through review and checking by individuals not directly responsible for the initial work product Take responsibility for the QA/QC of a project, regardless of role

22 Objective is to produce plans that: Are designed free of errors and omissions Contain all design elements to be complete and thorough Are appropriately designed Conform to the policies and procedures defined in the relevant TxDOT manuals, and to the guidelines on the TxDOT website Clearly define the sources of information for the calculations and the interface with related documents Result in constructible plans

23 Participants, BRG Style Supervisor/Group Leader Design Engineer Checker Technician Engineer-of-Record

24 Outline 1. The need for QA/QC 2. Definitions 3. QC as it applies to bridge design 4. QA for the Bridge Division Design Section 5. Records retention

25 How do we get Quality Control in bridge design? Designer Prepare relevant, appropriate calculations and sketches Present the calculations and sketches in a neat and logical manner that is conducive to checking Conform the calculations and design sketches to the policies and procedures defined in the relevant TxDOT Manuals Perform all calculations on TxDOT calculation sheets, on spreadsheet equivalents or with TxDOT approved software

26 How do we get Quality Control in bridge design? Checker Check each component to ensure compliance with the policies defined in TxDOT Manuals and guidelines on the TxDOT website Check the calculations for internal consistency and traceability of sources Check the calculations, assumptions, given values, formulas, omissions, and accuracy Check methodology, reasonableness of results, and constructability

27 Close the Loop Design Designer Check Checker Checker Verify Designer Correct

28 What about the Plan Sheets? Technician Develop all details in accordance with Bridge Detailing Manual and applicable Bridge Division policies and practices Designer Check the details for completeness, technical adequacy and conformity to applicable standards, and for consistency with the corresponding calculations Check individual drawings using appropriate checklists for errors, completeness, conformance, and consistency

29 Close the Loop, deux Detail Technician Check Designer Designer Verify Technician Correct

30 Outline 1. The need for QA/QC 2. Definitions 3. QC as it applies to bridge design 4. QA for the Bridge Division Design Section 5. Records retention

31 Quality Assurance The supervisor/group leader is responsible for Quality Assurance The supervisor/group leader confirms the QC process by reviewing the QC cover sheet and the detail title block The supervisor/group leader completes a review of the details for constructability, applicability, completeness, and conformity

32 Quality Control Cover Sheet

33 Outline 1. The need for QA/QC 2. Definitions 3. QC as it applies to bridge design 4. QA for the Bridge Division Design Section 5. Records retention

34 Records Design Request Submittal Correspondence Calculations Details Any other documents required for design, such as existing plan sheets and review comments

35 Design Notes Required Calculations establishing the bridge s superstructure design satisfies controlling load cases and limit states for Girders or beams Stringers Floor beams Trusses Arches and hangers Cable stays

36 Design Notes Required Calculations establishing the bridge s substructure design satisfies controlling load cases and limit states for Cap beams Columns, Towers, and Pylons Other elements not specifically excluded

37 Design Notes Required Calculations establishing the bridge s foundation design satisfies design requirements for Piling Drilled shafts Spread footings Other elements not specifically excluded

38 Design Notes NOT Required Elements excluded if per current TxDOT Manuals and standard drawings Decks Bearings Railings Expansion joints Standard round columns if column height and diameter is within prescribed limits Abutment design Pile and/or Footing design

39 Questions? Thanks for your attention. Tom Stout TxDOT Bridge Division Design